1. Field of the Invention
The present invention relates to a display technology field, and more particularly to a TFT substrate, a TFT switch and a manufacturing method for the same.
2. Description of Related Art
A thin-film-transistor (TFT) based on oxide semiconductor is a hot research point for a further display field, and is widely studied and researched in the recent years. Wherein, an amorphous indium gallium zinc oxide (a-IGZO) compound thin film functions as an active channel layer has a high mobility up to 80 cm2/Vs (a mobility of an amorphous silicon only 0.5˜0.8 cm2/ Vs). Besides, the a-IGZO thin film is compatible with large-scaled a-Si mass production processes. Thus, the IGZO thin film has a great application future in a next generation LCD and organic light emitting diode (OLED).
However, a schottky contact is formed when a metal is contacted with the IGZO thin film. At a contact interface, the semiconductor band is bended so as to form a barrier. The existence of the barrier results in a large interface resistance, that is, a schottky resistance. The schottky resistance cause an insufficient on-state current of a TFT device, too large subthreshold swing (SS), and decreasing a stability of the device such that a display quality is affected.
Accordingly, decreasing the contact resistance between the metal and the IGZO thin film in order to form an ohmic contact is an important factor for deciding the performance of a semiconductor device. In the conventional art, one way to form the ohmic contact is performing a heavy doping (n+IGZO) at a semiconductor region contacted with the metal such that a depletion region of the interface becomes narrow, and electrons have more opportunities to pass through directly (tunneling effect). However, the conventional art for forming the ohmic contact requires an additional doping process so as to increase the manufacturing cost.